We have determined the prevalence and significance of exercise- induced frequent or repetitive ventricular ectopic beats (VEB) in apparently healthy BLSA volunteers. Between 1974 and 1984, 80 of 1160 such asymptomatic subjects developed frequent VEB (more than 10%) or salvos (greater than or equal to 3 in a row) on at least one maximal treadmill exercise test. These 80 subjects were significantly older than the larger group without such exercise- induced VEB (63.8+12.5 vs. 50.0+16.1, p less than .0001). Only 9 of 80 (11%) demonstrated an ischemic ST segment response to exercise response to exercise. Over a mean followup of 4.6 years; only 2 cardiac events have occurred. A prolongation of the QT interval, whether, occurring naturally or induced by drugs or electrolyte imbalance, has been associated with major ventricular arrhythmias. To investigate such as association in apparently healthy subjects, we measured the QT interval at rest (R) maximal exercise (Ex) and recovery (Post EX) in 31 BLSA volunteers with exercise-induced nonsustained ventricular tachycardia (VT) and in 31 BLSA age- and sex-matched subjects without exercise-induced VT). Mean heart rate (beats/min) did not differ between control and VT subjects at rest (72 vs. 78), maximal exercise (147 vs. 142) or recovery (102 vs. 98) respectively.